In known digital cellular radio configurations a represented by FIG. 1, the system comprises a number of base stations 10, 13, 16 each of which are connected to a local exchange for mobile systems 11, 14 and 17 (i.e. mobile switching centres). The blocks 11, 14 and 17 are connected to the telco (e.g. British Telecom) network via switches 12, 15 and 18 which allow communication with geographically remote users via switches 22, 25 and 28, exchanges 21, 24 and 27 and base stations 20, 23, 26. To illustrate operation mobile telephone users 30, 31 are shown communicating with telephone users 46 and 45 respectively.
Users 30 and 31 happen to be using the same base station 13, and users 45 and 46 are using geographically adjacent stations 23. The active exchanges 14 and 24 will pass the voice information between the users and will also provide location control information which voice and control information will pass as packets of digital data through the telco network (which may include digital exchanges 15 and 25 with optical fibre interconnections).
When a user (say user 30) who is on the move passes closer to one of the base stations 16, the system has the capability to switch communications to the geographically closer base station and in practice the user's telephone will request the base station to accept transmission and this will be handled by the exchange 17 to ensure the call is routed to the correct destination. This will require the switch 18 to link with switch 25 (as shown by the broken line connection).
With increasing popularity, because of greater density of traffic use, the FIG. 1 configuration becomes saturated when the number of users either initiating a call or moving to other base stations is high.
In a Globecomm 88 paper titled `The ATM Zone Concept` by Foster and Adams, a possible solution is described which employs a network architecture based on ATM (Asynchronous Time Multiplexing).
The present invention is concerned with a mobile system with improved capabilities which can make use of this zonal concept.
According to the invention there is provided a mobile communications system including: a plurality of base stations, routing means for connecting any base station to any other base station, a plurality of means each associated with one of said base stations for packetising control and packetising data signals and a plurality of means each associated with one of said base stations for tracking the current physical address within a packet switched network of a moving terminal to which control and/or data packets are to be passed and from which control and/or data packets are received.
Further according to the invention there is provided a method of controlling a mobile communications system having a plurality of base stations, the method comprising: providing a routing path for connecting any base station to any other base station, providing at each station packetising control information and packetising data information and providing at each station tracking of the current physical address within a packet switched network of a moving terminal to which control and/or data packets are to be passed and from which control and/or data packets are received.